The present invention relates data storage devices and methods of operation thereof and, more particularly, to data storage systems using multiple storage devices sharing a common data channel and methods of operation thereof.
Computer systems, such as desktop computers and notebook computers, may include a main memory and an external storage device. It is generally preferable that the external storage device provide high storage density at a relatively low price.
Commonly used external storage devices include hard disk drives (HDDs) that use disk storage media. Such disk storage devices may provide a large capacity at a relatively low price, but their operations may include relatively complex mechanical operations, such as mechanical control of a magnetic transducer head. Disk storage devices may also be vulnerable to damage from physical impacts, and may be regarded as having a relatively low reliability.
Traditional semiconductor memories, such as DRAM or SRAM, have not generally been used as alternatives to disk-based external storage. Although semiconductor-type external memory devices may provides faster access than disk drives and be less vulnerable to mechanical damage, there may be several drawbacks of using such devices for external mass storage. For example, price per unit capacity of SRAM devices tends to be high in relation to disk drives. Additional power needed to retain data in DRAM devices may increase the cost of using such devices. Power consumption associated with DRAM refresh operations may make it difficult to use DRAM in mobile applications.
Flash memory based devices, however, may provide viable alternatives to disk drives for external storage. Typical flash memory devices may be programmed more than once. Flash memory devices may also have a relatively simple structure, which may make fabrication less costly. Flash memory devices may be low-power, compact, light and resistant to physical impact, so they may be suitable for use in mobile applications.